1. Field of the Invention
The present invention relates to a spacer that is used in a linear transmission element and operates between balls of the linear transmission element, this spacer will not tip over under the effect of gravity or centrifugal force, thus enabling the linear transmission element to operate more smoothly.
2. Description of the Prior Art
Since linear transmission products are being applied more and more widely in the modern industry, various linear transmission mechanisms have widely come into human life, manufacturing factory and high science and technology instruments, such as linear guideway, ball screw, and the like. Particularly in a large-scale precision mechanism are usually installed various large and small ball screws or linear guideway systems. Although the technology for linear transmission element is developing fast, consumers still need the technology to be improved uninterruptedly. Therefore, there are still some problems to be solved. And this desire for constant improvement of technology is particular strong in many high precision mechanism-manufacturing fields that require comparative stability and quiet. Hence, the existing linear mechanism still has some technological blind spots to be improved.
As shown in FIG. 1, a conventional ball screw system is usually provided with a plurality of spacers 11 arranged between the balls 10 for prevention of impact, abrasion and noise. Most of the spacer 11 products are required to be miniaturized, unitary and made of single material, however, they not practical because of the following reasons:
Since intervals must be reserved between each pair of balls 10 during installation of balls 10 into the ball screw, for enabling the balls 10 to roll smoothly (balls will not be jammed in the system). However, if the reserved intervals between the balls 10 are gathered together, it will form a space that is large enough to make the spacers 11 fall down easily, and the spacers 11 fell down on the surface of the screw shaft 16 will interfere the operation of the balls 10. As shown in FIG. 5, the center of gravity of the spacers 11 will be kept in a tipped over position under the effect of the rotation of the screw shaft 16. Therefore, the spacers 11 are impossible to stand up automatically, and this will probably cause failure of the whole ball screw system.
In use, the non-uniform rotating speed of the balls 10 also will result in an occurrence of an overlarge distance between the balls 10, making it impossible to hold the spacers 11 firmly. Therefore, the spacers 11 are likely to tip over or to rub against the helical grooves of the screw shaft and the nut, adversely affecting the service life and the efficiency of the ball screw and the linear guideway.
Hence, with the popularization of the linear transmission application, the demand of solving the aforementioned problems is becoming more and more urgent, and manufacturing a ball screw less susceptible to failure has become the most important selling point that the manufactures are striving for. Therefore, how to develop a linear transmission element more satisfying the user's needs has become a focal point in the linear transmission unit manufacturing field.
What follows are some examples of the existing products:
As shown in FIG. 2, wherein each of the spacers 11 is designed to use flat surface and arc surface to contact the balls 10, the spacers 11 are arranged between the balls 10 and each is formed in both lateral surfaces with a left and right cavities 12 and 13. However, when the reserved intervals between the balls 10 are gathered together, the spacers 11 also will fall down easily without the possibility of standing up again (as shown in FIG. 5), thus causing failure of the whole ball screw system.
FIG. 3 shows a structure disclosed in U.S. Pat. No. 6,513,978, wherein an annular groove 14 is formed in the outer surface of the respective spacers 11. However, when the reserved intervals between the balls 10 are gathered together, the spacers 11 also will fall down easily without the possibility of standing up again (as shown in FIG. 5), thus causing failure of the whole ball screw system.
FIG. 4 shows a structure disclosed in U.S. Pat. No. 6,347,558, the inner and outer cross sections of the spacers 11 are Gothic-shaped so as to have a smooth arc surface 15. Although this type spacer 11 is able to roll when tipping over, it is still unable to stand up again when it completely falls down on the screw shaft 16 (as shown in FIG. 5), causing failure of the whole ball screw system.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.